The present invention relates to a detection apparatus and method used for detecting an angular velocity of an object, and to an electronic apparatus equipped with the detection apparatus.
Up to now, so-called gyro detection apparatuses have been widely used as angular velocity sensors for consumer use. The gyro detection apparatuses are sensors that detect angular velocities by allowing a cantilever vibrator to vibrate at a predetermined resonance frequency and detecting Coriolis force generated due to an influence of the angular velocity by a piezoelectric element or the like.
The gyro detection apparatuses have advantages in that the sensors have a simple mechanism, require short time to activate, and can be manufactured at low costs. The gyro detection apparatuses are mounted to, for example, electronic apparatuses such as a video camera, a virtual reality apparatus, and a car navigation system, and are used as sensors in shake detection, motion detection, and direction detection, respectively.
In recent years, the gyro detection apparatuses are required to be downsized and improved in performance due to the downsizing and improvement in performance of the electronic apparatuses to which the gyro detection apparatuses are mounted. For example, because of multi-functionalization of the electronic apparatuses, demands are made to mount the gyro detection apparatus to a substrate in combination with various sensors for other purposes, thereby reducing a size thereof. A generally-used technique for realizing such reduction in size is called MEMS (Micro Electro Mechanical System) which involves using an Si substrate and forming a structural body using a thin-film process and a photolithography technique used in forming semiconductors.
Incidentally, a vibration system becomes light along with the downsizing of the gyro detection apparatus. However, because the Coriolis force is proportional to the weight of the vibration system, detection sensitivity deteriorates that much. Further, because amplitude of the vibrator becomes small when a power supply voltage is decreased due to the downsizing of the gyro detection apparatus, the detection sensitivity also deteriorates thereby. An S/N of a detection output signal is degraded by the deterioration of the detection sensitivity.
Thus, to solve the problems as described above, there is disclosed a technique in which drive signals having the same phase and amplitude and output from two detection electrodes are added in an adding circuit and the signal whose phase has been inverted in an inversion circuit is input to the two detection electrodes (see, for example, Japanese Patent Application Laid-open No. 2000-205861 (paragraphs (0005) and (0016), and FIG. 1)).
However, recently, further downsizing and reduction in voltage of a vibration gyro are required. Therefore, there is a need to further improve detection sensitivity of the vibration gyro and a need for suppressing noises to obtain a higher S/N than ever before.